In recent years, environmental consciousness has increased and it is an important subject to reduce the power consumption of electronic equipment. In a video display device which displays a video signal, especially a video display device using a self-luminous light element (for example, a PDP (plasma display panel) or an organic EL device), reduction of power consumption is important and power-saving technology is required. A document 1 (Published Japanese patent application 2002-116728) discloses a technology for power-saving. According to the document 1, a characteristic amount calculating unit extracts the average luminance level of an input video signal (or the average picture level: APL), and a conversion processing unit converts the input video signal according to the extracted average luminance level.
In the conventional art, the average luminance level of the input video signal is regarded as an index of power consumption reduction. Therefore, when a plurality of video signals expressing mutually different images are inputted, if the average luminance level of these images is constant, the processing for reducing power consumption will become the same (regardless of how to control the image so that the average luminance level of the image becomes constant, as long as the average luminance level of the image itself is constant).
A new technology which can further reduce the power consumption of electronic equipment based on the conventional art is required.